Radio transmission.



H. 5. VAN DER BUL.

RADIO RANSMISSION APPLICAION HLED AUG.30. 19|5 Patented Apr. '22, 1919 van der Bijl.

duce mucli larger ch circuit of a th RADIO TRANSMISSION.

T0 aZl whom it may concem:

Be it known that I, HENDRIK JOHANNES VAN DER BIJL, a subject of the King of Great Britain, residing at N ew York, in the county of N ew York and State of New York, have invented certain new and usefnl Improvements in Radio Transmission, of which the following is a. full, clear, concise, and exact description.

. his invention is varied or modulated in accordance with the wave forms of telephonic ortelegraphic currents.

It has been found, in attempts to develop the art of radiotelephony, that limitaton has been imposed by reason of the act'that any telephone transmitter at resent own te the-art is incapable of hun dling all the ener which is required for successful modulat1on of hi h frequency power for commercial radiote ephony. The present invention, therefore, provides a, method in which it is not ne cassary that the %uired to ra ia.tecl from the antenne. h1s method depends upon the fact that an electromo tive force ut audion type produces an a1pparent change in the impedance of 1ts output circuit; in partzcular, a change in electromot1ve force 1mprewed upon the input circuit, resulting' from a change in impedance in a local circuit associated with said input circuit, causes the ilnpedance of the output circuit of the amp er to vary in such a way as te produce therein much ter ch-anges in power than ta.ke lace in te above mentoned ical circuit. e thermionic ampli'fier in this case acts as a magni g device for changes of power in the locsl circuit, and on account 0 this property a, primary source of modu- Iated power, capable of handling only a small amount of power, ma. be used to r anges, or example, m a. transmttmg anterna.

The object of this invention is, therefore, accumplished by inserting such a variable impedance path, for example, the output ermionic repeater, into the tral1smitting antenna, sa.id antenne carrying Specifleation of Letters Patent. Application flled August 30, 1915. Serlal ll'o.

Patented Apr. 22, 1919. 47,9%.

and thereby prohigh radiated power at frequency currents, ducing large changes in th changes of power in the primary modulating source, which may be a telephone transmitter or a telegraph key.

In this specification the antenna is taken to be the aerial and its ound connection, that is, the continuous highuency path from the free extremity of the aerial to the ground and the immediate source of electromagnetic waves in the ether. It may includo a condenser, and therefore need not be a complete metallic path.

he nature of this invention will be more clearly understood by reference to the drawings, in which Figure 1 repreSents one etniment of this invention, showing a method of connection of en amplfier in series h en antenne; Fig. 2 represents a preferred' form which is better adapted to the modulation of large amounts of power, such as would be required in commercial operaton; and Fig. 3 shows another method of placng the amplifier eflectively in series with the antenne by means of a transformer.

Re erring to Fig. 1, 1'8 is an antenne or a b frequency line; 2 an alternator or other source of high frequency currents; 3

generator 2; 4 is a therm1omc ampl1fier of the-audion type having an electron-emitting cathode 5, a grid 6, and a plate 7. The antenna system is earthed at the point 8. The plate circuit is completed through the choke coil 10 and the battery 9. A transformer 11 serves to impress upon the input circuit of the amplifier variations in electromotive force due to the operation of the microphone 12 in the local circuit. Batteries 13 and 14 are connected as usual in the oper ation of the emplxfier, and battery 15 supplies cu}1;rent to microphone 12.

antenna cir- To overcome this dfliculty, and to provide also for the modulation of larger ber of these ele In connecting such thermionic elements in parallel, t is necessary only to connect respectively all the cathodes, all the grids and all the plates. The cathodes may be heated hy separate batteries, as shown, or may be connected in parallel or in series en opemted from one hattery. In Fig. 3 the variahle impedance of the output circuit is placed directiy in the generator circuit, but since that circuit is coupled to the antenne by transformer 3, this output circuit is efectively in series with the antenne and generator, since an impedance that is connected into a circuit by means of a trans'ormer is equivalent, for forced oscillations, to a certan ether impedance connected directly into that circuit. The function of the choke coil mis te exclude direct current from the generator 2.

The opcration of the system is as follows:

The generator 2 impresses high-frequency power upon the antenne. Due to the choke coil 10, practically the whole of the high frequency current must flow through the amplifier and is snperposed upon the space current of the amplifier. The choke oil is necessary in order to pro"ide a conducting path for direct current in the output circuit. variation in resistance in the microphone 12, due to voice waves impinging upon it, causes an electromotive force to be impressed upon the input circuit, which, in consequence of a. well known property of the amplifier, produces an apparent change in the output resistance of the device, this change in output resistance causingt change in the ampli tude of the high-frequency antenna current. Further, since the thermionic amplifier is a non-distorting device, the impedance changes in its output circuit are copies of the impedance changes in the microphone c1rcu1t.

this mventwn Although is descrihed as applied to a Wireless transmitting system, it is obvious that instead of the antenne shown a wire circuit may be substituted, for example, a telephone line, without in any way departing from the idee underlying the invention. therefore, desire not to limited to a. wireless transmitting system, butintend this invention to include the use of this modnlating apparatus in connection with wire systems, as well as with Wireless systems.

What is claimed is:

1. A modulating system comprising en aan tenna to be supplied with signal waves, means for supplying high requency power to be modulated to said antenna, en audion havin a cathode and iary e ectrode, means for serially introducing the mpedance between said anode and cathode into said antenne, and means or controlling the potential of said auxiliary electrode in accordance with a. signal.

anode and an aux1l- 2. A modulating system comprising an antenna to be supplied with si gnal waves, means for supplying high requency power to be modulated to said antenne, an audion havin a cathode and anode and an auxiliary e ect ode, means for serially introducing the impedance hetween said anode and cath0de into said antenna, whereby all of said high frequency power said anode and said cathode, andmeahs for controllin the potential of said auxiliary electrode in accordanee with a signal.

3. In a radio transmission system, en antenna, a source of oscillations connected thereto, an asymmetric thermionic impedance element in series with said antenne, said impedance element having a cathode, an anode and an impedance controlling element, and means for varying the potential of said IJ3onflrolling &lement with respect to said cathode to vary the impedance of said thermionic element in accordance with signals.

4. In a system for radio transmission, an antenna, a thermionic cathode and an anode in an evacuated vessel and serially included in said antenne, an impedance control electrode in said vessel, means for impressing en electromotive force of signal wave form upon said electrode, and means or impressing high frequency power to be modulated upon said antenne.

5. In a radio signaling system, an antenna, a thermionic impedance in 'series therewith carrying all the antenna current, said impedance having SP&CQ current electrodes directly connected te pointe in said antenne and an impedance controlling element, and signaling means for varying the potentie] ofsaid impedance controlling element with respect to one of said space current electrodes.

6. In an electrical transmission system, the combination With a transmission circuit by which energy is transmitted directly from one station to enother, of a space discharge device having en anode, a. cathode and an impedance varying element, said device being included serally in said circuit so that all of said energy of said transmission circuit passes through said discharge device and means for applying a low signaling frequency electromotive 'r'orce loetween said cathode and said impedance varying element.

7. A high frequency circuit by means of which energy is dire0tly transmitted to a distant station, en asymmetric thermionic device in series arrangement in said circuit, said impedance device having a cathode, en anode and an impedance controlling element, cnd means for varying the potential of said controlling element With respect to said cathode to vary the series impedance of said circuit in aocordance with signals.

flows between 8. A hi h frequency circuit including a source of igh frequency current, an asymmetric thermionic impedance device in series arrangement in said circuit, said impedancc device having a cathode, an anode, a source of space current, and an impedance controlling element, means for varying the potential of said controlling element with respect to said cathode te vary the series impedance of said circuit in accordance with signals, and means associated with said circuit to transmit energy varying proportionally to that of the current in said circuit.

9. A transmittin station comprising an electron discharge evice having-a cathode, an anode and an impedance varying element, a source of unidirectional electromotive force in circuit with said cathode and anode, and an alternating current source in series with said cathode and anode.

10. A transmitting station comprising an electron discharge device having a cathode, rn anode and a grid, an input circuit connected to said cathode and grid, signaling means associated with said input circuit to control the impedance of said device, a source of unidirectional current in a circuit connecting said cathode and anode, and an alternating current source in a. series circuit with.said cathode and anode.

11. In combination, a plurality of electron discharge devices, each having a. cathode, an anode and a grid, an input circuit having ons terminal connected te each of said cathodes andthc ether terminal connected te each of said grid elements, signaling means associated with said input circuit to control the impedance of said electron discharge dcvices, a source of unidirectional electromotive force having ons terminal connected te each of said cathodes, and the other connected to each of said anodes, and means fur supplying alternating current in series circuit with said cathode and anode.

12. A transmitting station comprising an electron discharge device having an anode, a cathode and an impedance varying element, a source of unidirectional electromotive force in a series circuit including said anode and cathode, and a source of alter nating electromotive force in a second series circuit including said anode and cathode.

13. A transm1tting station comprising an electron discharge device having an anode, a cathode and an impedance varying ele ment, a source of unidirectional electromotive force in a series circuit including said anode and cathode, a source of alternating electromotive force in a second series circuit including said anode and cathode, and means in one of said series circuits for preventing flow of current therein caused by said source of electromotive force in the other of said series circuits.

14. A11 electron dischargc device having an anode, a cathode and an impedance varying element, a source of unidirectional (lec tromotive force in a series circuit including said anode and cathode, a source of alternating electromotive force in a second series circuit including said anode and cathode, means in the first of said series circuits ior preventing current therein from said source of elcctromotive force in the second of said series circuits, said second circuit being of such character that substantially no current from the source of electromotim force in said first circuit can flow therein.

In witness whereof, 1 hereunto subscribe my name this 27th day of. .'\ugust, A. D. 1915.

HENDRIK JHANNES nu een BUL. 

